Colorectal cancer is the third most common cancer diagnosed in men and women (excluding skin cancers). This year alone, more than 93,000 people in the United States will be diagnosed with colon cancer, and nearly 40,000 will be diagnosed with rectal cancer, according to the American Cancer Society. Fortunately, advances in treatment mean more than 1 million colon cancer survivors are living in the US, and newer screening techniques are finding and removing polyps before they develop into cancer, dramatically dropping the death rate from colorectal cancer and improving patient outcomes.
Diets high in processed meats and red meat may increase a person’s risk of developing colorectal cancer. A 2015 study found a Mediterranean diet high in fruits, vegetables, and fish may reduce the risk of colorectal cancer by 43% -- an even greater effect than an all-vegetarian diet. Heavy alcohol consumption, smoking, obesity, type 2 diabetes, family history of cancer, or personal history of bowel disease (such as inflammatory bowel disease [IBD], but not irritable bowel syndrome [IBS]) also increase risk. Ashkenazi Jews have a high risk for developing colorectal cancer, and African Americans have the highest rates of colorectal cancer incidence and mortality in the US.
The United States Preventive Task Force recommends regular screening for colorectal cancer using fecal occult blood testing, sigmoidoscopy, or colonoscopy in adults beginning at age 50 and continuing until age 75, or beginning earlier in those at high risk. The Centers for Disease Control and Prevention clarify these tests as follows:
- High-sensitivity fecal occult blood test (FOBT), which checks for hidden blood in three consecutive stool samples; should be done every year.
- Flexible sigmoidoscopy, where physicians use a flexible, lighted tube (sigmoidoscope) to look at the interior walls of the rectum and part of the colon; should be done every five years with FOBT every three years.
- Colonoscopy, where physicians use a flexible, lighted tube (colonoscope) to look at the interior walls of the rectum and the entire colon; typically done every 10 years. During this procedure, samples of tissue may be collected for closer examination, or polyps may be removed. Colonoscopies can be used as screening tests or as follow-up diagnostic tools when the results of another screening test are positive. Colonoscopy also is used as a diagnostic test when a person has symptoms, and it can be used as a follow-up test when the results of another colorectal cancer screening test are unclear or abnormal
These guidelines are currently being updated as newer, less invasive technologies such as fecal immunochemical tests (FIT) and fecal DNA testing become more widely available.
If colorectal cancer is found, surgery is often the first-line treatment. Some colorectal cancers are contained in the end of a polyp, which can be removed, potentially during colonoscopy. Colectomy, segmental resection, or proctectomy with colo-anal anastomosis refer to procedures where a cancerous piece of the colon or rectum is removed and the remaining tissue is re-attached.
In some cases, there is not enough tissue to restore the colon, so one end must be attached to the abdominal wall so the stool can empty into a bag outside the body, known as a colostomy. An ileostomy is performed when the end of the small intestine must also be used. If rectal cancer spreads into nearby organs, pelvic exenteration may be performed, removing the rectum, bladder, prostate or uterus. If the bladder is removed, a urostomy (external opening to collect urine) is also necessary.
Risks of surgery may include bleeding, infection, damage, or complications with anesthesia. Common side effects include pain and nausea.
If surgery is not an option, ablation, cryosurgery, or embolization may be recommended. Radiofrequency ablation (using high-energy radio waves to kill tumors) may be used. A physician uses ultrasound or CT to guide a needle-like probe directly into the tumor, then releases a current that destroys cancer cells. An ultrasound or CT may also be used for ethanol ablation, directly injecting alcohol into a tumor. Cryosurgery uses a metal probe guided by ultrasound to freeze a tumor and destroy it. Embolization blocks or reduces blood flow to cancer cells in the liver, sometimes using tiny beads containing chemotherapy or radiotherapy agents.
Chemotherapy may be recommended to treat remaining cancer cells or address areas that cannot safely be surgically removed. Targeted therapies designed to specifically attack colorectal cancer cells are used for advanced cancers, and are being evaluated for their potential as part of adjuvant therapy for earlier stage cancers to reduce the risk of recurrence. Immunotherapy, currently available only in clinical trials, is being explored for its potential to boost a patient’s existing immune system to promote the body’s ability to fight cancer more effectively.
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Newly diagnosed with colon cancer? Find support for yourself and friends and family through the Colon Cancer Alliance.